1. Field of the Invention
The present invention relates to a method of manufacturing a reflector comprising a fiber-reinforced plastic material (hereinbelow, referred to as a FRP) which reflects light ranging from infrared rays to visible rays.
2. Discussion of Background
FIG. 4 is a schematic view in cross-section of a conventional reflector during manufacture and FIG. 5 is a cross-sectional view of the reflector as a manufactured product.
In FIGS. 4 and 5, the reference numeral 1 designates a forming mold, a numeral 2 designates a reflecting film formed on a convex surface of the forming mold 1 by vapor-deposition, and a numeral 3 designates a product as a material to be shaped by molding which is formed by impregnating previously a reinforcing fabric material with a resin (the product being referred to as a prepreg) which is pressed on the forming mold 1. A character A designates a reflection mirror comprising an FRP plate 4 and the reflecting film 2, the FRP plate 4 being obtained by compressing and heating the prepreg 3, followed by curing it.
In the conventional manufacturing method, the forming mold 1 finished with a given accuracy to have a predetermined shape is prepared; the reflecting film 2 such as an aluminum film is formed on a surface of the mold 1 by vapor-deposition; the prepreg 3 is laminated on the reflecting film 2; and compressing and heating the laminated body followed by curing of a resin impregnated with the prepreg 3, whereby the shape of the forming mold 1 is transferred to the FRP 4. Thus, the reflector A of the FRP is prepared as shown in FIG. 5.
FIG. 6 is a schematic view in cross-section showning another method of manufacturing a conventional reflector. The reflector prepared by the method as shown in FIG. 6 has a sandwiched structure unlike the reflector having a single FRP as shown in FIG. 5.
In FIG. 6, reference numerals 4, 4a designate FRP plates and a numeral 5 designates a core material constituted by a honeycomb body or a flexible core body made of a thin metallic plate or a fiber-reinforced plastic plate, or a polymeric foamed body. The core material 5 is bonded to the FRP plates 4, 4a by an adhesive 6.
In the manufacturing method as shown in FIG. 6, a reflector A having the sandwiched structure is obtained by forming the reflecting film 2 on the forming mold 1, laminating the prepreg 3 on the reflecting film 2, heating the prepreg 3 under a pressure to form the FRP plate 4, putting on the FRP plate 4 the core material 5 and the FRP plate 4a (which is prepared separately), and bonding these members by the adhesive 6.
In the conventional methods of making the reflector, a cavity or a recess is produced in the reflecting surface due to shrinkage of the prepreg 3 while the resin cures. The cavity or the recess reduces accuracy in the mirror surface, hence, the percentage of normal reflection is reduced.
The conventional method also has such disadvantage that the reflecting film 2 can not be removed to correct the shape of the reflecting surface or to finish the surface to improve the surface roughness when the molded product does not have a desired shape and accuracy even though the forming mold 1 having a predetermined shape with a given accuracy is used.